Repair Notes Sony SLV-679HF Video Cassette Recorder

Date: 2/2013

Problem:

Owner wrongly connected unit to 220V power source and damaged the unit’s power supply.

Diagnosis:

One 125V 2A fuse was blown. Fuse replaced and blew again immediate which meant there was a short circuit somewhere. Although not entirely relevant to the power supply, ICP-N5 (IC protector fuse) was checked and is good.

Upon closer inspection, found a burned voltage-dependent resistor (PCB part label VDR-601, 10mm, 240V). In addition, an inductor or coil used as line filter was damaged by the burned VDR or varistor. One of its wires broke from the base. (PCB part label LF600) 1-416-929-11 FILTER, LINE 

Repair:

Fuse was replaced with a 250V 2A. The important thing is that the current rating is exactly the same. The voltage difference is not a problem.

The varistor is not essential for the operation of the power supply, and it is difficult to find. The VCR operates without it, however, a 10mm 430V (10V431) replacement was installed.

It is very difficult to find a Sony or equivalent replacement part for the broken inductor LF600. Eventually, the only practical solution is to add an addition piece of copper wire to extend the reach of the broken wire in order to attach it to the base connector.

After the above replacement were made, the VCR powered, however its original (PCB part label C605, 200V, 120µF) began to release heavy smoke from the top vent, render it unusable. An exact replacement is difficult to obtain, hence a 400V capacitor with similar capacitance is used.

Result:

After the replacement of these components, the VCR powers on normal. However, during play back, the picture would show very briefly on the screen and disappear. The screen becomes blue. In addition, the timer does not run. The VCR does not stop playing the cassette, only there is not image. Pressing Fast Forward or Rewind in play mode shows the images, but when it stops, the picture stabilizes briefly and disappears again.

Diagnosis of playback problem:
After cleaning the drum head of the VCR, which was dirty with a ring of deposit on the surface, the picture problem persists. Since the mechanical part seems functional, the problem may lie in the secondary power supply. The first thing to try is the capacitor.

Repair of the picture problem:
Two capacitors were replaced: 6.3V 470uf (PCB label C617), 10V 1500uf (PCB label C613).

Result:
The picture problem went away and the VCR is working normal again. In order to find exactly which capacitor caused the problem, each new capacitor was replaced with the old one to see if the problem repeats. However, even when both old capacitors were again placed, the picture problem did not occur. To ensure the future reliability of its operation, the new capacitors were put back again.

 

 

Parts Replacement List

Label on PCB	Sony Part Number and Name	Original Value	Replaced Value
LF600	1-416-929-11 FILTER, LINE	--	Repaired
VDR-601	1-801-445-31 VARISTOR TNR10V241K660	240V 10mm diameter	430V 10mm dia.
C605	1-119-882-51 ELECTROLYTIC CAPACITOR (BLOCK)	120uF 20% 200V	150uF 20% 400V
F600	1-533-296-11 FUSE, GLASS CYLINDRICAL	120V 2A	250V 2A
C617	Electrolytic Capacitor	16V 470uF	16V 470uF
C613	Electrolytic Capacitor	10V 1500uF	10V 2200uF

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